The invention relates to an electrical plug-in connection, comprising a plug part and a mating plug part, which can be plugged together and produce a large number of electrical connections, at least the plug part or the mating plug part bearing, on its body, a union nut, which can be screwed to the mating plug part or the plug part and secures the plug-in connection against becoming disconnected in an undesirable manner, the union nut having, at its ends, an internal thread for screwing it to the plug part and the mating plug part, and the internal threads being formed in the opposite direction.
Such plug-in connections are generally known and are in use and are preferably used in the construction of electrical appliances, machines, vehicles and systems. The intention is therefore to provide the fitter or the user with a possibility of producing or detaching an electrical connection simply, rapidly and safely. In this case, the connection technology is designed such that it safely connects the contact elements electrically to one another and protects any personnel coming into contact with the plug-in connection against hazardous voltages. For this purpose, plug-in connections are often used which comprise a multi-pole plug part with female contact connectors and a multi-pole mating plug part with male contact connectors, which are designed such that they largely protect the electrical contact elements against mechanical and atmospheric influences.
It is known in this case to secure the plug part and the mating plug part against becoming disconnected in an undesirable manner by means of a union nut. For this purpose, the union nut, which is borne, for example, by the plug part, is screwed onto an external thread of the mating plug part until it reaches an axial stop and is tightened firmly. A sealing ring is often provided between the plug part and the mating plug part, which sealing ring is pinched when the plug connection is plugged together or when the union nut is screwed on and seals the plug part and the mating plug part with respect to one another. In addition, the sealing ring may act as a friction brake for the union nut and prevent the screw connection from becoming detached in the event of vibrations. In this case, O rings have proven particularly successful as sealing rings and as a friction brake during manufacture and in industrial use.
One disadvantage of these known plug-in connections is the time required for screwing and unscrewing the union nut when producing or when disconnecting the plug-in connection. Another disadvantage is the fact that, in the case of a sealing ring which is arranged between the front faces of the plug part and the mating plug part, the sealing ring is not always pinched such that it seals the annular gap between the plug part and the mating plug part reliably against the ingress of moisture. This is particularly the case when plug parts and mating plug parts of various manufacturers which are conventional on the market are used in pairs, since in this case there is often a slight play. This also results in the union nut becoming detached by means of vibration movements.
However, stringent requirements as regards the robustness, resistance to vibration, the ability for them to be fitted rapidly and sealtightness are placed on the above plug-in connectors for industrial use.